@misc{indiciae571447ac6440,
  title = {The ancient oxygen exosphere of Mars: Implications for atmosphere evolution},
  author = {Zhang, M. H. G. and Luhmann, J. G. and Nagy, A. F. and Bougher, S. W.},
  year = {1992},
  url = {https://ntrs.nasa.gov/citations/19920019837},
  note = {Source identifier: 19920019837}
}